In a study published in the Journal of the National Cancer Institute, researchers analysed whether coffee can protect against cutaneous melanoma: malignant melanoma and melanoma in situ.Tetra Pak/Flickr

Having a cup of coffee early in the morning is thought to be the best way to start a day.  However, it turns out that the time at which the coffee is consumed is more important to get the desired results.

According to Steven Miller, a neuroscientist at the Uniformed Services University of the Health Sciences in Bethesda, Maryland in the US, consuming coffee between 9.30 a.m. and 11.30 a.m. provides the best results, The Telegraph reported.

Miller, on a blog, explained how the habit of drinking coffee between 8 a.m. and 9 a.m. can have a negative impact as it is the time when the level of hormone cortisol is high in the body. 

Cortisol is an important hormone produced by the adrenal gland. The hormone plays a major role in maintaining the body's metabolism and stress. Dysregulation of the hormone has been widely known to cause many deadly diseases. Cortisol levels usually go up after waking up in the morning and stay high for a few hours between 7-9 a.m. 

The high cortisol production early morning helps keep the body alert and consuming caffeine at that time will be less effective, encouraging people to consume larger amounts.  

"If we are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it.  This is because cortisol production is strongly related to your level of alertness and it just so happens that cortisol peaks for your 24 hour rhythm between 8 and 9 AM on average," he wrote.

"Therefore, you are drinking caffeine at a time when you are already approaching your maximal level of alertness naturally. One of the key principles of pharmacology is use a drug when it is needed. Otherwise, we can develop tolerance to a drug administered at the same dose. In other words, the same cup of morning coffee will become less effective and this is probably why I need a shot of espresso in mine now."

So he recommended people to delay their morning coffee and consume it after 9 a.m. when the cortisol levels start going down, and until 11.30 a.m. when the levels continue to remain low.